Aptitude - Pipes and Cistern - Discussion

Discussion Forum : Pipes and Cistern - General Questions (Q.No. 13)
13.
A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?
3 hrs 15 min
3 hrs 45 min
4 hrs
4 hrs 15 min
Answer: Option
Explanation:

Time taken by one tap to fill half of the tank = 3 hrs.

Part filled by the four taps in 1 hour = 4 x 1 = 2 .
6 3

Remaining part = 1 - 1 = 1 .
2 2

2 : 1 :: 1 : x
3 2

x = 1 x 1 x 3 = 3 hours i.e., 45 mins.
2 2 4

So, total time taken = 3 hrs. 45 mins.

Discussion:
53 comments Page 1 of 6.

Sriramamurthi said:   5 years ago
Guys, it is very easy.

A tap can fill a tank by 6 hrs. Then one tap is closed after 6 hrs which means 6/2=3 hrs.
Then 3 more taps are opened so now totally there are 4 taps are opened.
We are having remaining time will be 6-3 =3 hrs.
So find 3/4 you get 0. 75 hrs which means 45 mins.
So the Answer will be 3hrs 45 mins.
Hope it will help you.
(12)

GAGAn said:   5 years ago
It is assumed that all the taps are equally efficient, so we have divided 3 hrs, i.e 180 min into 4 equal part, that how 45 min came.
(11)

Hemanth said:   2 years ago
We know Rate * Time = Capacity.

Rate = 1/6 ,
Capacity = 1/2.
1/6 * time =1/2
Here time = 3hrs for capacity half.
Next, more three pipes total of 4 pipes.
4 * 1/6 = 2/3.

Rate for 4 pipes is 2/3, Time=?, Capacity = another 1/2,
2/3 * time = 1/2.
Here time = 3/4 = 0.75hrs(0.75*60min).
Total time = 3hrs + 0.75hrs(45 min).
(9)

Debapriya paul said:   7 years ago
1/6 part filled by one tap in 1 hr.
1/2 part filled by one tap in 3hrs.
Part filled by 4 taps in 1hr is 4 * (1/6)=2/3.
2/3 part filled by 4 taps in 1 hr.
1/2 part filled by 4 taps in 3/4 hr.
So , total time = 3hr + (3/4)hr.
=3 hr 45 mins(answer).
(9)

Teja said:   4 years ago
Time taken by 1tap to fill the tank is 6hrs, then half is 3hrs (work done by 1 tap).
So,
3 * (1/6) + x * (4/6) = 1,
x = 3/4.
(5)

Tushar Pawar said:   3 years ago
They asked total time, so half tank is filled in 3 hour and later it takes 45 min as we calculated. Therefore 3 hour and 45 min.
(3)

Aadarsh kumar said:   5 years ago
As we know, rate * time =capacity.

So, after half filled.
A*3=4A *t
t=3/4 hour.
So total time taken is the time taken by A to fill half i.e 3 hr + 3/4 hr = 3 hr 45 minutes.
Thanks.
(3)

Sapna Singh Lodhi said:   7 months ago
The half tank filled in 3 hours since the full took 6 hours.
So, the rest half will be filled by 4 tap = 3 * 60/4 = 45.
Complete time to fill the tank = 3 hours 45 min.
(2)

Faysal said:   6 years ago
Quick one:
1 pipe fills half of the tank=6/=3 hrs.

Remaining half,
1 pipe takes 3 hr.
4 '' '' =3/4 hr= 45 mins.
Total = 3hrs+45mins(Answer)
(2)

Gunjan said:   6 years ago
Thanks @Faysal.
(1)


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